I have an OS Max .50 FSRH (helicopter engine) and it really runs nice but it has very little compression compared to my other engines. (I use it on a plane as I gave up on Choppers for a few years.) Is this normal? I really never noticed it until a buddy was looking at it and was spinning the prop with his hand. It is ringed could that have something to do with it?

Again, thanks for all your help. Some day it will be me helping someone!